Positioning and locking device

ABSTRACT

A device for positioning and locking rods, pins or wires, particularly for an external fixator in the field of orthopaedics is provided. The device comprises two jaw faces and a tightening assembly exhibiting a connecting element secured to a tightening member, the assembly allowing the jaws to form at least one opening exhibiting at least one cavity in the form of a gripping jaw allowing a hoop, a rod, a pin or a wire to be clipped by pressure against the action of an elastic member keeping the device in position prior to the locking action which is performed using the tightening member.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. Ser. No. 09/473,588 filed Dec. 28, 1999 claiming priority of Swiss patent application 2582/98 filed Dec. 29, 1998.

BACKGROUND OF THE INVENTION

[0002] The subject of the present invention is a device for positioning and locking rods, pins or wires, particularly for an external fixator in the field of orthopaedics. More particularly, it relates to a clamping device used as a support piece in osteosynthesis and osteoplasty to be incorporated into external fixator elements when a bone is fractured.

[0003] There are a great many support pieces or clamps on the market for producing fixation assemblies to meet the ever-increasing demands of orthopaedic surgery. Those selected should be those which are more able to fulfil their function through their simplicity and their ease of handling, time being an extremely important factor in such operations. Although external fixators have been in existence for some time, the support pieces are still evolving in order to provide better solutions for various problems often encountered.

[0004] U.S. Pat. Nos. 4,784,125 and 5,095,919 relate to a hoop element and also an external fixator in which this hoop element is incorporated with the members for fixing pins and wires intended to be used in osteosynthesis and osteoplasty.

[0005] European Patent EP 0 321 472 (WO 8801152) describes an articulation element for the relative positioning of fixing rods or bone pins of an external fixator. This articulation element comprises a number of pairs of gripping jaws which on the adjacent faces exhibit slots which form a passage intended to accommodate a rod or a pin. The angular position between the said pairs can be locked and there is a tightening element passing through the said pairs of gripping jaws to tightly clamp the rods or pins in a relative position. Furthermore, the gripping jaws which form a pair are equipped respectively with a positioning projection and with a cutout of a complementing shape.

[0006] U.S. Pat. No. 5,752,954 relates to an articulation device for components of an external fixator. This device allows for the relative positioning of fixing rods or pins and comprises two pairs of gripping jaws arranged in such a way that an elastic element acts against the gripping jaws and press the adjacent faces of the gripping jaws in order to lock the articulation device. In their adjacent faces, the gripping jaws have slots which are positioned and arranged in such a way to exhibit an opening allowing a rod or pin to be clamped by pressure. The teachings of U.S. Pat. No. 5,752,954 are incorporated herein by reference.

[0007] The holding and clamping devices known from the prior art have the disadvantage of not holding themselves in a chosen position when they are attached to rods, bars or pins. The user therefore has to maintain the correct relative positioning of the rods, pins and wires until such time as he performs the tightening or locking operation.

SUMMARY OF THE INVENTION

[0008] The object of the present invention is to overcome this drawback and to provide a device which holds itself in its assembled position, which can be adjusted, until such time as the assembly is tightened or locked.

[0009] The present invention corresponds to a device for positioning and locking rods, pins or wires, particularly for an external fixator in the field of orthopaedics. The device comprises two external jaws and a tightening assembly. The tightening assembly has a connecting element secured to a tightening member. The assembly allows the jaws to form at least one opening exhibiting at least one cavity in the form of a gripping jaw allowing a hoop, a rod, a pin, bar or a wire to be clipped by pressure against the action of an elastic member which keeps the device in position prior to the locking action which is performed using the tightening member.

[0010] According to one embodiment, the connecting element is a bushing which passes through the two jaws and can have placed inside it a retained rod which is designed to be locked with the jaws by the tightening member. The elastic member is a spring in the form of a staple connecting the two jaws, at the opposite side of which is the clipping or gripping zone which has the opposing clamping faces; it may be a single or double spring. The free ends of the staple forming the spring are introduced into orifices in the jaws. According to another embodiment, the elastic member is an axial tension or coil spring. In both embodiments, the two jaws have assembly notches which position them relative to one another.

[0011] The jaws and the bushing have devices which prevent one from rotating relative to the other. The upper jaw member has a conical recess and a cylindrical bore for accommodating the bushing, the lower jaw having a bore which has two opposed flat surfaces to play a part in mating with the bushing, the latter having two opposed flat surfaces in its central part in the direction of its axis which correspond with those of the lower jaw member to make it easier to fit into the said lower jaw face.

[0012] The bushing, which is cylindrical, has an upper part in the form of a truncated cone with slots in the direction of its axis to allow the rod to be clamped tightly once it has been placed inside it. The bushing has its lower part threaded with a diameter appropriate to that of the tightening nut.

[0013] According to another embodiment, the connecting element is a shank passing through a ring connected to a rod, the upper jaw being placed at one of the ends of the shank, around which the lower jaw and the tightening nut are positioned.

[0014] According to this same embodiment, the two jaws exhibit an opening in the form of a gripping jaw with at least one cavity allowing a pin or a wire to be clipped and then clamped within the jaws. The two jaws have balls made of a hard material placed alternately between the cavities to assist with locking the wire housed inside it.

[0015] The nut is advantageously produced in the form of a ribbed knob screwed around the lower part of the shank which allows the entire device to be kept assembled. A toothed annulus is inserted between the ribbed or knurled knob and the post to set the angular position of the device which will thereafter remain locked once the ribbed knob has been tightened. The device comprises an axial helical spring between the ring and the toothed annulus.

[0016] According to a third embodiment, the connecting element is in the form of a bolt, the free end of which is threaded to screw into a bore in the post, the bolt passing through a clamp delimiting at least one gripping jaw in the form of a slot placed transversely with respect to the connecting element, the material placed between the bottom of the slot and the external surface of the clamp acting as a spring.

[0017] According to any one of the embodiments, the device is able to act as a support piece for an external fixator comprising a circular or part circular hoop formed from a bar of specified cross-sections, pins, bars or wires or rods, in which fixator the devices exhibit outer openings allowing the clipping of the hoop, of the pins and of wires and the fixing of the rods or of the said devices by their posts so that by tightening the devices, it is possible to achieve relative positioning thereof prior to locking.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawing illustrates, by way of examples, some embodiments of the device with a clipping gripping jaw according to the invention.

[0019]FIG. 1 is a perspective view of a first embodiment of the device of the present invention;

[0020]FIG. 2 is a cross-sectional view through the device of FIG. 1;

[0021]FIG. 3 is a section through the device of FIG. 1 with an alternative form of elastic member;

[0022]FIG. 4 is a perspective view of another embodiment of the device;

[0023]FIG. 5 is a cross-sectional view through the device of FIG. 4;

[0024]FIGS. 6 and 7 show the device of FIG. 4 holding respectively a pin and a wire in its gripping jaw;

[0025]FIG. 8 is a cross-sectional view through the device according to a third embodiment of the invention; and

[0026]FIG. 9 shows part of an external fixator for osteosynthesis and osteoplasty, in which a series of devices with clipping or gripping jaws of the present invention are shown as support pieces for positioning rods, pins and wires cooperating with a hoop.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Referring to FIGS. 1 and 2, the positioning and locking device, generally denoted as 1 is made up of an upper jaw member 2 and a lower jaw member 3 having opened faces which are machined with assembly notches 4 to allow one to be positioned and pivoted against the other, leaving an opening 5 at the opposite end. A bushing or hollow shaft 6 passes through the two jaws 2, 3 at right angles, through the opposite end of the jaws with respect to the gripping jaw opening. As best seen in FIGS. 2 and 3, bushing 6, at its upper part 7, has the shape of a cone frustum with slots 8 which start from this upper part 7 and run in the direction of the axis of the bushing to end about halfway down the length thereof. The lower part of bushing 6 is threaded at 9 and is screwed into a nut 10 which clamps the two jaws 2, 3 together.

[0028] A spring in the form of a staple 11 a or bent wire is housed inside holes 12 each made in each one of the jaws 2, 3 also on the opposite side to the opening of the gripping jaw. Upper jaw 2 has a conical recess in its upper part and a cylindrical bore to accommodate bushing 6 and lower jaw 3 has a bore which has two opposed flat surfaces to play a part in holding bushing 6 in place especially against rotation, these flat surfaces not being depicted in the drawing. Bushing 6 has a smaller diameter in its threaded lower part 9 and in its central part has two opposed flat surfaces, not shown in the drawing, which engage the flats on lower jaw 3 to prevent bushing 6 from rotating relative to the jaws and allow the nut to be locked.

[0029] Between bushing 6 and the bores of jaw 2, 3 there is a clearance that allows the jaws device 1 to be pivoted outwardly against the face of staple spring 11 a, prior to the tightening operation. The clearance allows the jaws 2, 3 to be parted just enough for clipping an element between the faces of each jaw, for example, onto a rod or a hoop along which device 1 can slide and therefore change position. A rod 13 may be inserted into bushing 6 and locked in position by the clamping action of the conical position of the upper part of bushing 6 which deforms inwardly as nut 10 is tightened pulling the bushing downwardly into the conical recess of upper jaw 2. This causes upper part 7 of bushing 6 to deform inwardly in the area of slots 8. This rod 13 may remain fixed in a concrete assembly position so that one can adjust the relative positions of all the elements of the device prior to the final operation of tightening the assembly.

[0030]FIG. 3 shows in section the device of FIGS. 1 and 2 in which the elastic member is now an axial tension spring 11 b which, in its equilibrium portion, keeps the two jaws 2, 3 assembled, allowing them to open during the clipping operation and holding the device locked until final tightening is performed using the nut 10.

[0031] Referring to FIGS. 4 to 7, there is shown another embodiment in which the device 11 consists of a tie bolt 20, which at one of its ends has an upper jaw member 21 with balls 22 made of a material which is harder than the piece being clamped, these balls being made, for example, of ceramic or of a hard metal. Placed around the tie bolt 20 in succession are a lower jaw member 31 with other balls 32 made of any material that is harder than the piece to be held, the two jaw 21, 31 creating an outer opening 51 with two cavities 52, 53; a spiral spring 40, a post 61 ending in a ring 62 at one of its ends. Ring 62 may have teeth arranged therearound for engaging a toothed plate 71. A nut in the form of a ribbed knob 81 is threaded onto end 20 a of the bolt 20. FIGS. 6 and 7 show how the device 11 clips a pin 16 in its outer cavity 52 or a wire 17 in its inner cavity 53.

[0032]FIG. 8 shows a third embodiment with a nut 82 as its connecting element. The part 75 is a clamp with sets of gripping jaws with openings 85, in which pins or wires can be clipped. The elastic element may be incorporated into the clamp and may be in the form of a thin piece of material located away from the openings and acting as a spring. The elastic element may be in the form of a narrow slit between adjacent jaw faces terminating in a small through bore 111 adjacent to the bottom of part 75. As the bolt 82 is tightened in threaded bore 84 of post 161, the narrow slit is closed with the thin metal of clamp 75 around bores 111 acting as a spring.

[0033] According to the first embodiment, bushing 6 which passes through two jaws 2, 3 is fitted into upper jaw 2 with the aid of the cone frustum shape of its upper part, which rests against the similarly shaped recess of the upper jaw. The rod 13 is inserted into bushing 6 to finally be tightened using nut 10. This nut has a large head to make it easier to tighten by hand before being locked using any appropriate tool when the system is in place. Device 1 with rod 13 in place is clipped via its outer opening 5 by lateral pressure onto a hoop or bar 91 and remains in this position by virtue of the action of the spring 11 a, 11 b. It goes without saying that any other form of opening is envisageable without departing from the scope of the present invention, to allow the device to be clipped onto any other part, not depicted.

[0034] According to the second embodiment, the two jaws 21, 31 use lateral pressure to clip a pin 16 or a wire 17 respectively in the outer cavity 52 or inner cavity 53, against the face of the spring 40. This spring is a spiral spring which, pressing against the ribbed knob 81, presses the lower jaw cheek 31 against the upper jaw cheek 21; the balls 22, 32 positioned in an offset configuration, retain the wire so that this wire cannot escape from the gripping jaw. The ribbed knob 81 presses the device-pin or device-wire assembly together and once the post 61, which has one end in the form of a ring 62, has been orientated into its final position, clamps it against the toothed plate 71 so that it remains locked. The ribbed knob 81 has square head, but it goes without saying that any other shape of head may be used without departing from the scope of the present invention. As in the first embodiment and for the same reason, it has a large head to make it easier to initially tighten it by hand before finally locking it when the system is in place.

[0035]FIG. 9 depicts a hoop, bar or ring element 91, without a complete circle being formed, which forms part of an external fixator 90. The hoop element has a section with a web at the center of rectangular overall shape which serves as an element for connecting to two lateral reinforcements of cross section that is symmetrical with respect to an axis perpendicular to the web, allowing the support pieces to be clipped onto the inside or onto the outside of the hoop, as required. This figure shows three devices with clipping type gripping jaws according to the first embodiment 1 which are clipped, two to the inside of the hoop, and the third to its outside. In all three instances, devices 1 are assembled with other devices 11 according to the second embodiment to show how the two embodiments 1, 11 according to the invention can collaborate with each other, post 61 of one of them becoming rod 13 of the other. Two pairs of devices 11 support two transfixing wires which pass right through a bone (not shown), a third holds a pin 16 which would also be inserted into another part of the bone. The combination of these elements, the hoop with pins, wires, rods and devices with clipping gripping jaws makes it possible to achieve relative positioning of items with respect to each other, tightening it by hand to thereafter lock it permanently while maintaining the relative positions between the various elements. The device of FIG. 9 may also be assembled using a second hoop 91.

[0036] Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. 

1. A clamp having first and second surfaces with an external surface extending therebetween for use in an external fixation system, comprising: at least one pair of jaws having adjacent faces separated by a slit, said slit intersecting said external surface and extending intermediate said first and second surfaces and terminating in an internal widened area adjacent a first part of said of the external surface of said clamp; a groove formed in at least one of said jaws open to a second part of said external surface of said clamp, said groove intersecting said slit; a clamping element for closing the slit and preventing the faces of said jaws from moving away from one another.
 2. The clamp as said forth in claim 1, wherein said groove and said widened area extend in parallel directions.
 3. The clamp as set forth in claim 2, wherein said first and second parts of said external surface are opposite one another.
 4. The clamp set forth in claim 1, wherein said widened area is spaced internally from said first part of said external surface by a thin piece of material acting as a spring.
 5. The clamp as set forth in claim 1, wherein said groove is sized to accept a rod, wire or pin.
 6. The clamp as set forth in claim 5, wherein the groove has a cross-section smaller than the rod, wire or pin to be placed therein so that upon insertion of said rod, wire or pin from a direction perpendicular to a longitudinal extent of said groove, said jaw faces are moved apart along said slit by deflecting said thin piece of material.
 7. The clamp as set forth in claim 1, wherein the clamping element is a bolt extending between said first and second surfaces.
 8. The clamp as set forth in claim 7, wherein said bolt extends through a bore located intermediate said internal widened area and said groove.
 9. The clamp as set forth in claim 8 having two pairs of jaws mounted on said bolt with each pair of jaws having faces separated by a slit intersecting a groove and an internal widened area.
 10. The clamp as set forth in claim 1 wherein said widened area is a through bore.
 11. An articulation element for the relative positioning of fixation bars, rods or pins of an external fixator, comprising a clamp having at least one pair of jaws mounted around an internal shaft and arranged along an axis of said shaft and having adjacent faces with at least one face having a groove extending in a direction transverse to said axis which groove forms a passage intended to receive said rod, pin or bar radially outwardly from said internal shaft; said pair of jaws having adjacent faces separated by a slit extending from said groove, around said shaft and terminating in an internal through bore adjacent a first external surface of said clamp, said bore spaced internally from said external surface by a thin piece of material of the clamp acting as a spring; a clamping element for clamping said pair of jaws together and locking said rods, bars or pins held between said jaws in a relative position; said groove forming said passage is positioned and arranged so as to have an external opening on a second external surface of said clamp opposite said first external surface and extending along said transverse direction allowing the bar, rod or pin to be placed in said passage by pressure in a direction perpendicular to both said axis of said shaft and said direction transverse to said axis against an elastic force developed by the movement of said faces away from one another deflecting the thin piece of material acting as a spring to hold the articulation element on the bars, rods or pins before the clamping element locks the pair of jaws, said passage formed by said groove having an initial cross-section smaller than a cross-section of said pins, rods or bars prior to the rod, bar or pin being placed therein.
 12. The articulation element as set forth in claim 11, wherein said elastic force acts in a radial direction of said groove.
 13. The articulation element according to claim 11, wherein the grooves are of a rounded cross-section.
 14. The clamp as set forth in claim 11, wherein said groove and said bore extend in parallel directions.
 15. The clamp as set forth in claim 11, wherein said groove is sized to accept a rod, wire or pin.
 16. The articulation element as set forth in claim 11, wherein said shaft is a bolt and said clamping element is a nut threaded onto said bolt for engaging one of said jaws.
 17. A clamp for an external fixation system comprising: a body having a first and second end separated by an external circumferential surface with a slit intermediate said ends; said slit open to said external surface of said body over less than the entire circumference thereof and a rod receiving opening extending into said slit and in communication with said external surface and a clamping element extending between said first and second ends internally of said rod receiving opening with respect to said external circumferential surface.
 18. The clamp as set forth in claim 17, wherein said rod receiving opening is a groove open to said external surface.
 19. The clamp as set forth in claim 18, wherein said slit terminates in an internal bore of said body.
 20. The clamp as set forth in claim 19, wherein said groove and said bore extend in parallel directions.
 21. The clamp as set forth in claim 20, wherein said internal bore is spaced internally from said external surface by a thin piece of material acting as a spring.
 22. The clamp as set forth in claim 21, wherein the clamping element extending through said body intermediate said internal bore and said groove.
 23. The clamp as set forth in claim 22 wherein said clamping element is a bolt.
 24. The clamp as set forth in claim 21, wherein the groove has a cross-section smaller than the rod, wire or pin to be placed therein so that upon insertion of said rod, wire or pin from a direction perpendicular to a longitudinal extent of said groove, said jaw faces are moved apart along said slit by deflecting said thin piece of material.
 25. The clamp as set forth in claim 18, wherein said groove is sized to accept a rod, wire or pin. 